JP3703416B2 - Droplet landing position measuring apparatus and droplet landing position measuring method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a droplet landing position measuring device and a droplet landing position measuring method, and more particularly to an ink liquid in an ink jet printer that ejects ink from a nozzle port of an ink jet head to land the ink on a recording medium and print an image. The present invention relates to a droplet landing position measuring apparatus and a droplet landing position measuring method for evaluating a droplet landing position.
[0002]
[Prior art]
Conventionally, various methods for measuring the landing positions of ink droplets ejected from the nozzle openings of the inkjet head of the inkjet printer have been proposed.
[0003]
In the method described in Japanese Patent Application Laid-Open No. 2000-62158, at least one ink droplet is ejected from an ejection port of an inkjet head, and landed on a recording medium such as paper that is located away from the ejection port surface, The ink droplets that have landed on the ejection port and the recording medium are imaged by an image processing camera arranged below the recording medium and processed to measure the respective coordinates, and the ink droplets that have landed and the coordinates of the ejection port It was a method of measuring the landing position.
[0004]
Also, the method described in JP-A-7-329302 is a droplet landing position inspection method for ejecting ink from nozzles of an inkjet head and printing an image on actual printing paper, and is a recording medium. This is an inspection method in which a line inspection pattern is printed on printing paper, ink is ejected onto the inspection pattern, and landing position deviation of ink droplets is visually determined.
[0005]
[Problems to be solved by the invention]
However, JP-A-2000-62158 and JP-A-7-329302 of the conventional example have the following problems.
[0006]
In the method of observing or measuring the landing position of the ink droplet by actually landing the ink droplet on the recording medium, the ink repelling or spreading at the time of landing, and the bleeding, the ink discharge port position is As a result, there is a problem that it is impossible to accurately measure in which part the ink droplet has actually landed. Furthermore, it is difficult to accurately measure the relationship between the position coordinates of the nozzle opening and the position where the recording medium is placed in a three-dimensional direction, and the landing position of the ink droplet on the nozzle opening is accurate. This causes a problem that it cannot be measured. Furthermore, due to the scattering of small droplets called satellites that are ejected along with the ejection of ink droplets, the main ink droplets and satellites overlap each other and land on the recording medium, making it difficult to accurately measure the landing position.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to provide a droplet landing position measuring apparatus and a droplet that realizes reliable measurement of the ink droplet landing position by ignoring the ink repelling, spreading, and bleeding when the ink droplet is landed on the recording medium. A landing position measuring method is provided.
[0008]
[Means for Solving the Problems]
According to the first aspect of the present invention, the liquid for evaluating the landing position of the ink droplet in the ink jet printer that prints an image by discharging the ink droplet from the nozzle opening of the ink jet head and landing on the recording medium. In the droplet landing position measuring apparatus, when the ink droplet is ejected in a direction intersecting with the sheet-like light emitted from the light-emitting means and the sheet-like light emitted from the light-emitting means, Reflected light or transmitted refracted light of the ink droplet And the nozzle mouth Based on the imaging means for imaging the image captured by the imaging means, By calculating the coordinates of the nozzle openings and the coordinates of the ink droplets, and comparing the calculated coordinates of the nozzle openings and the coordinates of the ink droplets, There is provided a droplet landing position measuring device comprising landing position measuring means for measuring the landing position of the ink droplet.
[0010]
In the droplet landing position measuring apparatus, the light emitting means emits two orthogonal sheet-like lights, and the ink droplets are turned into the sheet-like light toward the center of intersection of these sheet-like lights. Alternatively, it may be discharged vertically.
[0011]
In the liquid droplet landing position measuring apparatus, the image pickup unit is configured to input the two orthogonal sheet-like light incident units, and reflected light or transmitted refracted light of the ink droplet to be imaged at a predetermined magnification. And an expanding unit.
[0012]
The droplet landing position measuring apparatus may include an image processing unit that performs image processing on an image captured by the imaging unit.
[0013]
According to the second aspect of the present invention, the liquid for evaluating the landing position of the ink droplet in the ink jet printer that prints an image by discharging the ink droplet from the nozzle opening of the ink jet head and landing on the recording medium. In the droplet landing position measuring method, the ink droplet is ejected in a direction intersecting with the sheet-like light, and the reflected light or transmitted refracted light of the ink droplet with respect to the sheet-like light And the nozzle mouth Image By calculating the coordinates of the nozzle openings and the coordinates of the ink droplets, and comparing the calculated coordinates of the nozzle openings and the coordinates of the ink droplets. And a method for measuring a landing position of the ink droplet, wherein the landing position of the ink droplet is measured.
[0015]
In the above droplet landing position measuring method, the sheet-like light is composed of two orthogonal sheet-like lights, and the ink droplets from the ink jet head toward the center of intersection of these sheet-like lights. May be discharged perpendicularly to the sheet-like light.
[0016]
In the above droplet landing position measuring method, the unit that injects the two orthogonal sheet-like lights, and a unit that expands reflected light or transmitted refracted light of the ink droplet to be imaged at a predetermined magnification. You may image the said nozzle opening while imaging the reflected light or transmitted refracted light of the said ink droplet with the imaging means with which it comprised.
[0017]
In the droplet landing position measuring method, the captured image may be subjected to image processing to calculate the coordinates of the nozzle openings and the coordinates of the ink droplets.
[0018]
In the droplet landing position measuring method, the ink droplets may be ejected from the inkjet head in a direction intersecting the sheet-like light by positioning the inkjet head by positioning means.
[0019]
Further, the droplet landing position measuring apparatus of the present invention will be described with reference to FIGS. 1 and 2, and ink droplets are ejected from the nozzle opening (2) of the inkjet head (1) to land on the recording medium. In a droplet landing position measuring apparatus that evaluates the landing position of the ink droplet in an inkjet printer that prints an image, the light emitting means (4) that emits light, and the light emitted by the light emitting means are in sheet form When the ink droplets are ejected in a direction intersecting the sheet-like light changed by the light-changing means, Based on the image picked up by the image pickup means (8) and the image picked up by the image pick-up means while picking up the reflected light or transmitted refracted light of the ink droplet, seat A coordinate calculating means for calculating the ink droplet, and a landing position measuring means for comparing the coordinates of the ink droplet with the coordinates of the ink droplet and measuring the landing position of the ink droplet. It is.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
[First Embodiment]
Next, a first embodiment of the present invention will be described in detail with reference to the drawings.
[0021]
(1) Description of configuration
FIG. 1 is an explanatory diagram showing the principle of measuring the landing position of ink droplets ejected from an ink jet head of an ink jet printer according to the present invention. In FIG. 1, 1 is an inkjet head having nozzles, 2 is a nozzle port for ejecting ink droplets (hereinafter abbreviated as droplets), 4 is a laser light emitting unit that emits laser light, and 7 is an imaging device (CCD camera). It is an imaging incident optical unit equipped.
[0022]
The ejection direction of the droplet 3 ejected from the nozzle port 2 is a direction orthogonal to the sheet light (sheet-shaped laser light) 5 emitted from the laser light emitting unit 4 and laid out at an isolated position. The reflected light (or transmitted refracted light) 6 generated when the droplet 3 passes through the sheet light 5 is imaged by an imaging device (CCD camera) (see FIG. 2) having an imaging incident optical unit 7 for image processing. To obtain the coordinates of the droplet 3. Further, the position of the nozzle port 2 is also imaged by the imaging incident optical unit 7 (observation system) of the imaging device (CCD camera), and the coordinates of the nozzle port 2 are obtained by image processing.
[0023]
That is, the principle of measuring the landing position of the ink droplet in the present invention is to determine the landing position of the ink droplet by comparing the coordinates of the nozzle opening 2 of the ink jet head 1 with the coordinates of the droplet 3 in the above procedure. is there.
[0024]
FIG. 2 is a conceptual diagram showing a configuration example of a droplet landing position measuring apparatus (prototype) according to the first embodiment of the present invention. In FIG. 2, 8 is an imaging device (CCD camera), 9 is a lens unit, 10 is an X stage that moves the inkjet head 1 in the X direction (horizontal direction), and 11 is that the inkjet head 1 is moved in the Y direction (horizontal direction). Y stage to be moved, 12 is a Z stage for moving the inkjet head 1 in the Z direction (vertical direction), 13 is a tilting mechanism for moving the X stage 10 in the vertical direction, 14 is a laser displacement meter, and 15 is an X stage. A θ stage (rotation mechanism) for rotating 10 within a horizontal plane, 18 is an observation system optical axis.
[0025]
The inkjet head 1 having nozzles can eject droplets in the vertical direction in the figure. The inkjet head 1 can be operated three-dimensionally by an X stage 10, a Y stage 11, and a Z stage 12. In this case, the position resolution of the X stage 10, the Y stage 11, and the Z stage 12 is, for example, 0.1 μm. Furthermore, the inkjet head 1 can be positioned with a degree of parallelism in the rotational direction and height, for example, with an accuracy of 0.1 μm, by a rotating operation by a θ stage (rotating mechanism) 15 and a vertical operation by a tilting mechanism 13. It is.
[0026]
The inkjet head 1 is positioned by imaging the nozzle port 2 with an imaging device (CCD camera) 8 and moving it to the position of the origin on any monitor determined in advance by each axis manual operation, and finally image processing. The origin on the monitor is aligned with the center point of the nozzle port 2 with an accuracy of 0.1 μm or less. The parallelism in the height direction is measured with a laser displacement meter 14 having an accuracy of 0.1 μm or less, and the distance between the three points between the lower surface of the nozzle port 2 and the laser displacement meter 14 is measured. Display and bring out parallelism by manual operation. By the above operation, the nozzle port 2 is positioned at 0.1 μm or less in the XYZ-θ-height direction.
[0027]
In a state where the nozzle port 2 has been positioned, the nozzle port 2 is irradiated with halogen light obliquely from below, and in a state where the spot-like reflected light is incident on the image pickup device 8 from the nozzle port 2, Shoot. Thereafter, the nozzle port 2 is moved upward in the Z direction, and then ink is ejected.
[0028]
In the vertical direction of the inkjet head 1, two orthogonal sheet lights 5 having a width of 4 mm and a thickness of 10 μm are laid out so that the center of the intersection of the sheet lights 5 coincides with the position of the origin on the monitor. The position is adjusted during assembly. Since the laser light emitted from the laser light emitting unit 4 has a good compatibility with the imaging device (CCD camera) 8 and has a short wavelength, a YAG double harmonic green laser with a wavelength of 532 nm, which is good in accuracy, was used. The laser light is split in two directions by a fiber cable, split into two sheet lights 5 by a lens unit 9, and the path of the sheet light 5 is routed so that the split two sheet lights 5 are orthogonal to each other. It is changing.
[0029]
The liquid droplets are ejected toward the center of the intersection of the sheet light 5 and the reflected light generated when passing through the sheet light 5 is imaged by the imaging device (CCD camera) 8. In the imaging device (CCD camera) 8, two orthogonal light beams can be made incident by the imaging incident optical unit 7 having four mirrors and two 20-magnification microscopes. In this case, the imaging device (CCD camera) 8 is disposed at a position of, for example, 45 degrees obliquely below the reflected light (or transmitted refracted light).
[0030]
That is, the droplet landing position measuring device converts a laser light emitting unit 4 that emits laser light, a fiber cable (spectral means) that splits the laser light in two directions, and two orthogonal sheet lights 5. When a droplet is ejected in a direction intersecting with a pair of illuminating lens units 9 and two orthogonal sheet lights 5, the reflected light or transmitted refracted light of the droplet with respect to the sheet light 5 is imaged. An imaging device (CCD camera) that images the nozzle port 2, a coordinate calculation unit that calculates the coordinates of the nozzle port 2 and the coordinates of the droplet 3 based on an image captured by the imaging device (CCD camera), and a coordinate calculation unit Comparing the calculated coordinates of the nozzle port 2 with the coordinates of the droplet 3, it includes landing position measuring means for measuring the landing position of the droplet 3.
[0031]
(2) Explanation of operation
Next, the operation of the first embodiment of the present invention will be described in detail with reference to FIGS.
[0032]
FIG. 3 is a diagram showing an image taken by the imaging device (CCD camera) 8 of the landing position measuring apparatus shown in FIG. The white spot on the upper left is the image of the nozzle port imaged from the left side, the white dot on the upper right is the image of the nozzle port imaged from the right side, and the white spot on the lower left is the image of the droplet imaged from the left side. The white dot at the lower right is an image of a droplet imaged from the right side. In addition, the image of the nozzle opening is taken before taking the image of the droplet, and these images are included in the same photograph by image processing. That is, after the nozzle port is irradiated with halogen light obliquely from below and an image of the nozzle is taken, the nozzle port is moved upward in the Z direction. Then, a droplet is ejected from the nozzle port, and the ejected droplet is imaged. In this case, the image of the nozzle opening and the image of the droplet are formed at substantially the same height, but the heights are different at the time of image synthesis. The coordinate calculation means calculates the difference between the coordinates of the upper left white point and the lower left white point in the horizontal axis direction, and the difference between the upper right white point and the lower right coordinate of the horizontal axis. Based on the difference between the two, it is possible to calculate a two-dimensional deviation (displacement on the XY plane) of the coordinates of the droplet with respect to the coordinates of the nozzle opening when the nozzle opening is viewed from the vertical direction (Z-axis direction). The example in FIG. 3 is an example in which the coordinates of the nozzle and the coordinates of the droplet are well aligned.
[0033]
FIG. 4 is a diagram showing how the image processing software obtains the origin of the image captured by the imaging device (CCD camera) 8, that is, the liquid is formed by two observation optical axes 21 orthogonal to the droplet 3. It is a figure which shows that the droplet origin 22 is calculated | required. FIG. 4 shows that the image of the nozzle port 2 and the image of the droplet are captured as two images in the orthogonal direction. The origin 22 is obtained from the captured image by image processing software.
[0034]
In the droplet landing position measurement experiment of the first embodiment, the center of the nozzle port 2 of the inkjet head 1 is the origin (0, 0), and the liquid has an arbitrary number of ejections (1, 50, 100, 500, 1000, 5000). The result of obtaining the droplet landing position coordinates (μm) is shown in FIG. The ink is black, the laser is a green laser with 500 mW output of YAG second harmonic with a wavelength of 532 nm, the reflected light of the droplet is imaged by the imaging device (CCD camera) 8, and coordinates are measured by the image processing software for measurement. Asked.
[0035]
FIG. 5 is a diagram showing a nozzle port 22 and a nozzle port origin 20, and a droplet image 21 and a droplet origin 23 obtained from an image obtained by imaging the reflected light of the droplet. The deviation between the origins of the mutual causes variations in landing positions.
[0036]
As described above, in the measurement of the landing position of droplets ejected from the ink jet head 1 of the ink jet printer, the nozzle port 2 of the ink jet head 1 is positioned with high accuracy of 0.1 μm or less, and the ink repels and spreads at the time of landing. And, it was shown that the conventional problem that it was not possible to accurately measure which part actually landed with respect to the discharge port position by blurring could be solved.
[0037]
That is, according to the present invention, the problem of the ink jetting, spreading, and blurring at the time of landing of the droplet from the inkjet head 1 to the recording medium, which was a problem in the prior art, does not occur, and the landing position of the droplet is determined. It can be measured with high accuracy. Furthermore, due to the scattering of small droplets called satellites that are ejected along with the ejection of droplets, the main droplets and satellites overlap each other and land on the recording medium, making it difficult to accurately measure the landing position. Can be resolved. Once the droplet landing position is clear, the optimal discharge port (discharge port unit) in an inkjet printer can be developed quickly and reliably. By developing the optimal discharge port (discharge port unit) The effect brought about can contribute to the improvement of the printing position accuracy and the higher definition of drawing.
[0038]
[Second Embodiment]
Next, a second embodiment of the present invention will be described in detail with reference to the drawings.
[0039]
(1) Description of configuration
The principle of the liquid droplet landing position measurement (FIG. 1) and the configuration of the liquid droplet landing position measuring apparatus (FIG. 2) of the second embodiment of the present invention are the same as those of the first embodiment.
[0040]
(2) Explanation of operation
Next, the operation of the second embodiment of the present invention will be described in detail with reference to FIGS.
[0041]
In the landing position measurement apparatus of this time, which was experimentally produced in FIG. 2, the experiment was conducted by changing the laser to a 500 mW He—Ne laser. The He-Ne laser has a stable output waveform, can stabilize luminance, and can perform a reliable experiment. In addition, the laser is the most widely available laser because of its low cost. Naturally, the availability is also good, and there is no problem with the availability of lasers. The He—Ne laser is converted into sheet light having a width of 4 mm and a thickness of 10 μm by the lens unit 9. In this experiment, the reflected light when the droplets passed through the sheet light was captured. Black was used as the ink (black ink has a characteristic that it absorbs a lot of light and is difficult to transmit. Therefore, the reflected light is captured).
[0042]
FIG. 7 is a view showing an image of the nozzle port 2 of the inkjet head 1 and an image of a droplet imaged by the imaging device (CCD camera) 8. As in the first embodiment, it has been shown that the landing position can be measured by performing image processing on the captured image using image processing software.
[0043]
[Third Embodiment]
Next, a third embodiment of the present invention will be described in detail with reference to the drawings.
[0044]
(1) Description of configuration
The principle of the liquid droplet landing position measurement (FIG. 1) and the configuration of the liquid droplet landing position measuring apparatus (FIG. 2) of the third embodiment of the present invention are the same as those of the first embodiment.
[0045]
(2) Explanation of operation
Next, the operation of the third embodiment of the present invention will be described in detail with reference to FIGS.
[0046]
In the landing position measuring apparatus manufactured as a prototype in FIG. 2, the experiment was conducted by using a 500 mW He—Ne laser as a sheet light having a width of 4 mm and a thickness of 10 μm. The ink used was magenta of color ink. Magenta has a characteristic of transmitting laser light without substantially reflecting it in terms of transmittance. That is, the image to be imaged in this experiment is not an image by reflected light but an image by transmitted refracted light.
[0047]
FIG. 8 is a view showing an image of the nozzle port 2 of the inkjet head 1 and an image of liquid droplets imaged by the imaging device (CCD camera) 8. As in the first embodiment, it has been shown that the landing position can be measured by performing image processing on the captured image using image processing software.
[0048]
[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described in detail with reference to the drawings.
[0049]
(1) Description of configuration
The principle of the droplet landing position measurement according to the fourth embodiment of the present invention (FIG. 1) and the configuration of the droplet landing position measuring device (FIG. 2) are the same as those of the first embodiment.
[0050]
(2) Explanation of operation
Next, the operation of the fourth embodiment of the present invention will be described in detail with reference to FIGS.
[0051]
In the landing position measuring device of this prototype as shown in FIG. 2, the experiment was conducted with a laser of 500 mW Ar laser (argon laser) and sheet light with a width of 4 mm and a thickness of 10 μm. The Ar laser is characterized by high output and brightness. As ink, magenta of color ink was used as in the third embodiment. Magenta has a characteristic of transmitting laser light without substantially reflecting it in terms of transmittance. That is, the image to be imaged in this experiment is not an image by reflected light but an image by transmitted refracted light.
[0052]
FIG. 9 is a view showing an image of the nozzle port 2 of the inkjet head 1 and an image of liquid droplets imaged by the imaging device (CCD camera) 8. As in the first embodiment, it is shown that the landing position can be measured by performing image processing on the captured image using image processing software.
[0053]
[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described in detail with reference to the drawings.
[0054]
(1) Description of configuration
The principle of the droplet landing position measurement according to the fifth embodiment of the present invention (FIG. 1) and the configuration of the droplet landing position measuring device (FIG. 2) are the same as those of the first embodiment.
[0055]
(2) Explanation of operation
Next, the operation of the fifth embodiment of the present invention will be described in detail with reference to FIGS.
[0056]
In the landing position measuring apparatus of this prototype as shown in FIG. 2, the experiment was conducted by using a laser beam of 5 mW and a sheet beam having a width of 4 mm and a thickness of 10 μm. The semiconductor laser is characterized in that it is small in size, saves space, and is easy to handle. As ink, magenta of color ink was used as in the third embodiment. Magenta has a characteristic of transmitting laser light without substantially reflecting it in terms of transmittance. That is, the image to be imaged in this experiment is not an image by reflected light but an image by transmitted refracted light.
[0057]
FIG. 10 is a view showing an image of the nozzle port 2 of the inkjet head 1 and an image of liquid droplets imaged by the imaging device (CCD camera) 8. As in the first embodiment, it is shown that the landing position can be measured by performing image processing on the captured image using image processing software.
[0058]
[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described in detail with reference to the drawings.
[0059]
(1) Description of configuration
The principle of liquid droplet landing position measurement (FIG. 1) and the configuration of the liquid droplet landing position measurement apparatus (FIG. 2) of the sixth embodiment of the present invention are the same as those of the first embodiment.
[0060]
(2) Explanation of operation
Next, the operation of the sixth embodiment of the present invention will be described in detail with reference to FIGS.
[0061]
In the landing position measuring device of this prototype as shown in FIG. 2, the experiment was conducted by using a 100 W halogen lamp as the light source and sheet light having a width of 4 mm and a thickness of 10 μm. Halogen lamps do not have laser spectral interference and produce a wide range of light rays. The halogen lamp is a light source that is safe for handling. As the ink, magenta of color ink was used as in the third embodiment. Magenta has a characteristic of transmitting laser light without substantially reflecting it in terms of transmittance. That is, the image to be imaged in this experiment is not an image by reflected light but an image by transmitted refracted light.
[0062]
FIG. 11 is a diagram showing an image of the nozzle port 2 of the inkjet head 1 and an image of a droplet taken by the imaging device (CCD camera) 8. As in the first embodiment, it is shown that the landing position can be measured by performing image processing on the captured image using image processing software.
[0063]
[Seventh Embodiment]
Next, a seventh embodiment of the present invention will be described in detail with reference to the drawings.
[0064]
(1) Description of configuration
The principle of the liquid droplet landing position measurement according to the seventh embodiment of the present invention (FIG. 1) and the configuration of the liquid droplet landing position measuring apparatus (FIG. 2) are the same as those of the first embodiment.
[0065]
(2) Explanation of operation
Next, the operation of the seventh embodiment of the present invention will be described in detail with reference to FIGS.
[0066]
In the landing position measuring device of this prototype as shown in FIG. 2, the experiment was performed by using a 500 mW He—Ne laser as a sheet light having a width of 4 mm and a thickness of 10 μm. As the ink, magenta of color ink was used as in the third embodiment. Magenta has a characteristic of transmitting laser light without substantially reflecting it in terms of transmittance. That is, the image to be imaged in this experiment is not an image by reflected light but an image by transmitted refracted light.
[0067]
FIG. 12 is a diagram showing an image of the nozzle port 2 of the inkjet head 1 and an image of a droplet taken by a silver salt camera. As in the first embodiment, it is shown that the landing position can be measured by performing image processing on the captured image using image processing software.
[0068]
[Eighth Embodiment]
Next, an eighth embodiment of the present invention will be described in detail with reference to the drawings.
[0069]
(1) Description of configuration
The principle of the droplet landing position measurement according to the eighth embodiment of the present invention (FIG. 1) and the configuration of the droplet landing position measuring device (FIG. 2) are the same as those of the first embodiment.
[0070]
(2) Explanation of operation
Next, the operation of the eighth embodiment of the present invention will be described in detail with reference to FIGS.
[0071]
In the landing position measuring device of this prototype as shown in FIG. 2, the experiment was performed by using a 500 mW He—Ne laser as a sheet light having a width of 4 mm and a thickness of 10 μm. As ink, magenta of color ink was used as in the third embodiment. Magenta has a characteristic of transmitting laser light without substantially reflecting it in terms of transmittance. That is, the image to be imaged in this experiment is not an image by reflected light but an image by transmitted refracted light.
[0072]
FIG. 13 is a diagram illustrating an image of the nozzle port 2 of the inkjet head 1 and an image of a liquid droplet imaged by an electronic camera with a built-in C-MOS sensor. As in the first embodiment, it has been shown that the landing position can be measured by performing image processing of a captured image using image processing software.
[0073]
[Ninth Embodiment]
Next, a ninth embodiment of the present invention will be described in detail with reference to the drawings.
[0074]
(1) Description of configuration
The principle of the droplet landing position measurement according to the ninth embodiment of the present invention (FIG. 1) and the configuration of the droplet landing position measuring apparatus (FIG. 2) are the same as those of the first embodiment.
[0075]
(2) Explanation of operation
Next, the operation of the ninth embodiment of the present invention will be described in detail with reference to FIGS.
[0076]
In the landing position measuring device of this prototype as shown in FIG. 2, the experiment was performed by using a 500 mW He—Ne laser as a sheet light having a width of 4 mm and a thickness of 10 μm. As ink, magenta of color ink was used as in the third embodiment. Magenta has a characteristic of transmitting laser light without substantially reflecting it in terms of transmittance. That is, the image to be imaged in this experiment is not an image by reflected light but an image by transmitted refracted light.
[0077]
FIG. 14 is a diagram showing an image of the nozzle port 2 of the inkjet head 1 and an image of liquid droplets imaged by a one-dimensional line sensor. As in the first embodiment, it has been shown that the landing position can be measured by performing image processing of a captured image using image processing software.
[0078]
【The invention's effect】
As described above, according to the present invention, ink droplets are ejected in the direction intersecting with the sheet-like light, and the reflected light or transmitted refracted light of the ink droplet with respect to the sheet-like light is imaged, and the inkjet The nozzle port of the head is imaged, and the captured image is processed to calculate the coordinates of the nozzle port and the coordinates of the ink droplet, and the coordinates of the nozzle port and the coordinates of the ink droplet are compared. Since the landing position is measured, the ink at the time of landing, which is a problem in the method of observing and measuring the landing position by causing the ink droplets to actually land on the recording medium with high accuracy as in the past, is a problem. The repelling, spreading, and bleeding are ignored, and the landing position of the droplet can be reliably measured. Furthermore, as a ripple effect, problems and countermeasures for nozzle development are clarified, and it can be expected to realize a high-quality inkjet printer in a timely manner.
[0079]
That is, according to the present invention, there is no problem of ink repelling, spreading, and bleeding at the time of droplet landing on the recording medium from the inkjet head, which is a problem in the prior art, and the droplet landing position is increased. It can be measured with accuracy. Furthermore, due to the scattering of small droplets called satellites that are ejected along with the ejection of droplets, the main droplets and satellites overlap each other and land on the recording medium, making it difficult to accurately measure the landing position. Can be resolved. Once the droplet landing position is clear, the optimal discharge port (discharge port unit) in an inkjet printer can be developed quickly and reliably. By developing the optimal discharge port (discharge port unit) The effect brought about can contribute to the improvement of the printing position accuracy and the higher definition of drawing.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram illustrating the principle of landing position measurement of ink droplets according to first to ninth embodiments of the present invention.
FIG. 2 is a conceptual diagram showing a prototype of an ink droplet landing position measuring apparatus according to first to ninth embodiments of the present invention.
FIG. 3 is an explanatory diagram showing a nozzle port image and a droplet image captured according to the first embodiment of the present invention.
FIG. 4 is an explanatory diagram illustrating a state in which the origin of a captured image according to the first embodiment of the present invention is obtained by image processing software.
FIG. 5 is an explanatory diagram showing variation in droplets according to the first embodiment of the present invention.
FIG. 6 is an explanatory diagram showing a result of obtaining droplet landing position coordinates for an arbitrary number of ejection strikes according to the first embodiment of the present invention.
FIG. 7 is an explanatory diagram showing a nozzle port image and a droplet image captured in the second embodiment of the present invention.
FIG. 8 is an explanatory diagram showing a nozzle port image and a droplet image captured according to the third embodiment of the present invention.
FIG. 9 is an explanatory diagram showing a nozzle port image and a droplet image captured according to the fourth embodiment of the present invention.
FIG. 10 is an explanatory diagram showing a nozzle port image and a droplet image captured according to a fifth embodiment of the present invention.
FIG. 11 is an explanatory diagram showing a nozzle port image and a droplet image captured in the sixth embodiment of the present invention.
FIG. 12 is an explanatory diagram showing a captured nozzle opening image and a droplet image according to the seventh embodiment of the present invention.
FIG. 13 is an explanatory diagram showing a nozzle port image and a droplet image captured according to an eighth embodiment of the present invention.
FIG. 14 is an explanatory diagram showing a captured nozzle opening image and a droplet image according to the ninth embodiment of the present invention.
[Explanation of symbols]
1 Inkjet head
2 Nozzle port
3 droplets
4 Laser emission part
5 sheet light
6 Reflected or transmitted light
7 Imaging incident optical unit
8 Imaging device
9 Lens unit
10 X stage
11 Y stage
12 Z stage
13 Tilt mechanism
14 Laser displacement meter
15 θ stage

Claims (9)

In a droplet landing position measuring apparatus that evaluates the landing position of the ink droplet in an inkjet printer that prints an image by discharging an ink droplet from a nozzle port of an inkjet head and landing on a recording medium,
Light emitting means for emitting sheet-like light and reflected light of the ink droplet with respect to the sheet-like light when the ink droplet is ejected in a direction intersecting with the sheet-like light emitted from the light emitting means Alternatively, based on the image picked up by the refracted light and the nozzle opening, and the image picked up by the image pickup means, the coordinates of the nozzle opening and the coordinates of the ink droplet are calculated, the calculated coordinates of the nozzle opening and the A droplet landing position measuring device comprising: a landing position measuring means for measuring a landing position of the ink droplet by comparing the coordinates of the ink droplet. The light emitting means emits two orthogonal sheet-like lights and discharges the ink droplets perpendicularly to the sheet-like light toward the center of the intersection of these sheet-like lights. The droplet landing position measuring device according to claim 1 . The imaging means includes a unit that enters the two sheet-shaped light beams orthogonal to each other, and a unit that expands reflected light or transmitted refracted light of the ink droplet to be imaged at a predetermined magnification. The droplet landing position measuring device according to claim 2 . The droplet landing position measuring apparatus according to any one of claims 1 to 3 , further comprising an image processing unit that performs image processing on an image captured by the imaging unit. In a droplet landing position measuring method for evaluating a landing position of the ink droplet in an inkjet printer that prints an image by discharging an ink droplet from a nozzle port of an inkjet head and landing on a recording medium,
The ink droplets are ejected in a direction intersecting with the sheet-like light, the reflected light or transmitted refracted light of the ink droplet with respect to the sheet-like light and the nozzle port are imaged, and the coordinates of the nozzle port and the A droplet landing position measuring method comprising: calculating the ink droplet coordinates, and measuring the landing positions of the ink droplets by comparing the calculated coordinates of the nozzle openings and the coordinates of the ink droplets. . The sheet-like light is composed of two orthogonal sheet-like lights, and the ink droplets are perpendicular to the sheet-like light from the inkjet head toward the center of intersection of these sheet-like lights. The droplet landing position measuring method according to claim 5 , wherein the droplet landing position is discharged. The ink droplets are obtained by an imaging unit comprising the unit that enters the two orthogonal sheet-like lights and a unit that magnifies reflected light or transmitted refracted light of the ink droplet to be imaged at a predetermined magnification. The droplet landing position measuring method according to claim 6 , wherein the reflected light or transmitted refracted light is imaged and the nozzle port is imaged. The droplet landing position measuring method according to claim 5 , wherein image processing is performed on the captured image, and the coordinates of the nozzle opening and the coordinates of the ink droplet are calculated. . By positioning the ink jet head by the positioning means, to one of the claims 5 to 8, characterized in that for ejecting the ink droplets from the ink jet head in a direction crossing to said sheet of light The droplet landing position measuring method as described.

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